The mobile communication system has been developed for the user to communicate on the move. With the rapid advance of technologies, the mobile communication system has evolved to the level capable of providing high speed data communication service as well as voice telephony service. Recently, as one of the next generation mobile communication system, Long Term Evolution (LTE) is on the standardization by the 3rd Generation Partnership Project (3GPP). LTE is a technology designed to provide high speed packet-based communication of up to 100 Mbps and aims at commercial deployment around 2010 timeframe.
Meanwhile, unlike voice service, the data service is provided on the resource determined according to the data amount to be transmitted and channel condition. Accordingly, the wireless communication system, especially cellular communication, is provided with a scheduler manages transmission resource allocation in consideration of the required resource amount, channel condition, data amount, etc. This is the fact in the LTE system as the next generation mobile communication system, and the scheduler located at the base station manages the transmission resource allocation.
Recent studies are focused on the LTE-Advanced (LTE-A) for improving data rate with the adaptation of several new techniques to legacy LTE system. Carrier Aggregation (CA) is one of such technologies. CA is the technology that aggregates a plurality of carriers for uplink and downlink transmission between a User Equipment (UE) and an evolved Node B (eNB) so as to increases the data reception amount/reception data rate or transmission amount/transmission data rate in proportion to the number of aggregated carriers. In LTE, the cell operating on the main carrier frequency is referred to as Primary Cell (PCell) and the other cells operating on other frequency carriers are referred to as Secondary Cell (SCell).
Meanwhile, with the introduction of repeater and Remote Radio Head (RRH), the positions of antennas responsible for the radio transmission/reception change (e.g. the transmit/receive antennas for the secondary carrier may be located at the RRHs while the transmit/receive antennas for the primary carrier are located at the eNB) and, in this case, it is prefer to acquire the uplink transmission timing to a receive antenna near the terminal location rather than the uplink transmission timing to a receive antenna far from the terminal location.
This means that a plurality of uplink transmission timings may exist and thus there is a need of a method for managing carriers efficiently in a carrier aggregation scenario including a plurality of uplink transmission timings.